1. Field
The disclosed concept pertains generally to electric vehicles (EVs) and, more particularly, to electric vehicle supply equipment (EVSE), such as chargers for EVs.
2. Background Information
With the development of electric vehicle technology, the number of electric vehicles (EVs) is growing rapidly, and electric vehicle charging stations, similar to gas stations, have become popular.
An electric vehicle (EV) charging station, also called an EV charging station, electric recharging point, charging point, and EVSE (Electric Vehicle Supply Equipment), is an element in an infrastructure that supplies electric energy for the recharging of electric vehicles, plug-in hybrid electric-gasoline vehicles, or semi-static and mobile electrical units such as exhibition stands.
An EV charging station is a device that safely allows electricity to flow. These charging stations and the protocols established to create them are known as EVSE, and they enhance safety by enabling two-way communication between the charging station and the electric vehicle.
The 1996 NEC and California Article 625 define EVSE as being the conductors, including the ungrounded, grounded, and equipment grounding conductors, the electric vehicle connectors, attachment plugs, and all other fittings, devices, power outlets or apparatus installed specifically for the purpose of delivering energy from premises wiring to an electric vehicle.
EVSE is defined by the Society of Automotive Engineers (SAE) recommended practice J1772 and the National Fire Protection Association (NFPA) National Electric Code (NEC) Article 625. While the NEC defines several safety requirements, J1772 defines the physical conductive connection type, five pin functions (i.e., two power pins (Hot1 and Hot2 or neutral; or Line 1 and Line 2), one ground pin, one control pilot pin, and one proximity pin), the EVSE to EV handshake over the pilot pin, and how both parts (EVSE and EV) are supposed to function.
Two-way communication seeks to ensure that the current passed to the EV is both below the limits of the EV charging station itself and below the limits of what the EV can receive. There are additional safety features, such as a safety lock-out, that does not allow current to flow from the EV charging station until the EV connector or EV plug is physically inserted into the EV and the EV is ready to accept energy. For example, J1772 in North America uses a very simple but effective pilot circuit and handshake in the EVSE.
EV charging stations consist generally of a completely separate and special box with indicators for power and state along with a connected EV cable/connector for the intended purpose of charging the EV.
The connection between an electric vehicle and a charger within a charging station (also known as an EV charger) which supplies the EV with direct current during the charging process is shown in FIG. 1a. A charger 10 includes power converter 12, which further includes a system controller 122 and a power module 121. An electric vehicle 20 includes a battery management system (BMS) 21 and a battery 22. The system controller 122 is coupled to the BMS 21.
After the coupling of the charging circuit of the electric vehicle 20 and the charger 10, the system controller 122 and the BMS 21 send data to each other according to predefined protocols. The system controller 122 controls the power module 121, which charges the battery 22.
There are various types of communication protocols between system controller 122 and BMS 21, including, for example and without limitation, CHAdeMO, SAE (Society of Automotive Engineers), and IEC (International Electrotechnical Commission), as shown in Table 1.
TABLE 1Coupler StandardCommunication ProtocolSAE J1772Physical circuit of thecommunication protocol is powerline carrier communication (PLC)IEC 62196-3EC 61851-24 (over CAN bus)JEVS G105-1993CHAdeMO (over CAN bus)Chinese GBChinese GBSAE J1772 and IEC (IEC 62196-3) include coupler standards and communication protocol standards. Chinese GB is a national standard of China, which includes a coupler standard and a communication protocol standard. Each communication protocol has specific protocol specifications with respective address allocation modes, data package definitions and functions.
Therefore, as shown in FIG. 1b, an EV charger following a specific protocol can only connect to the BMS following the same protocol and charge electric vehicles following the same communication protocol, resulting in dedicated chargers for each protocol.
SAE has proposed a J1772 “Combo Coupler” or “combo connector” as an extension of J1772™. The J1772 combo connector includes additional pins to accommodate relatively fast DC charging at 200-450 Volts DC and up to 90 kW, and can employ Power Line Carrier (PLC) technology to communicate between an electric vehicle (EV), an off-board EV charger, and a smart grid. The J1772 combo connector includes AC L1, L2 and DC L1, L2 into the connector standard.
The CHAdeMO association and the China Standardization Committee also published a DC connector and communication standard between the EV and the EV charger.
While SAE's combo connector design indicates one technology trend during a transition period, an EV charger is desired to have the capability of both AC and DC.
There is room for improvement in electric vehicle supply equipment.